Final answer:
The minimum size planking for scaffolds commonly used and considered safe is 2" x 10". This size supports the necessary weight and complies with safety standards.
Step-by-step explanation:
The minimum size planking that can be used for scaffolds according to OSHA standards can vary, but typically, the smallest size that is deemed safe and commonly used is 2" x 10". Scaffold planks should be capable of supporting, without failure, their own weight and at least four times the maximum intended load. It is essential to ensure that the planks used meet the specific requirements for the type of scaffold and the load it will carry. Scaffolds must be designed by a qualified person and constructed and loaded in accordance with that design. Using undersized planking not only risks the safety of workers, but it also violates safety regulations.